Interfaces

Systems

Various

Gold Apollo AL-A28 (Pilot XP)

An obsolete pager can be converted into a single channel receiver for paging monitoring
by adding a discriminator output.

With the Gold Apollo AL-A28 POCSAG pager (sold in the US as 'Apollo Pilot XP'), it is not necessary
to solder at receiver IC, that has a high pin density.

Apollo AL-A28

Each pager contains a battery saving mechanism. At regular intervals, the receiver is switched on briefly to check if there are messages. If not, the receiver will sleep
until the next interval. To be able to use the pager as a monitoring receiver, this battery saving mechanism needs to be disabled to open the receiver continuously.
Obviously, as a result battery life will decrease considerably.

Follow the next steps to make a data output on the AL-A28:

Connect the two solder pads indicated. This enables continuous reception

Solder a miniature 10 k resistor to the test point indicated

Connect the resistor's other lead with a piece of insulated wire. If required, shrink tubing can be applied to isolate the resistor

Connect the other lead of the wire with the inner conductor of a piece of shielded cable. The shied can be soldered to the ground plane on the circuit board

Location of the solder pads

Connected solder pads and 10 k resistor

Overview

As there is not enough clearance for a chassis socket, you can drill a hole and lead the shielded wire outside. You can use a tyrap as strain relief.
The shielded wire can be terminated with a female 3.5 mm connector. This 'pigtail' enables using an interface or audio cable.

You can also box the pager and add a 1.5 Volt power supply. You can find a description here.